pennington



983 1929. a. R. PENNINGTON Re. 17,409

SHOCK ABSORBER FOR IOTOR VEHICLES Original Filed Jan. 5". 1922 msmswm H l 1 amuentom Reissued Au 20, 1929'.

GORDON R. PENNINGTO'N, F CLEVELAND HEIGHTS, OHIO, ASSIGNOR TO PENNINGTON ENGINEERING COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

SHOCK ABSORBER FOR MOTOR VEHICLES. v

Original application filed January 5, 1922, Serial No. 527,228. Renewed April 7, 1927. Original No.

1,677,405, dated July 1 7, 1928. Application for reissue filed June 10, 1929. Serial No. 369,831.

' of a spring equipped vehicle and the body or chassis frame thereof with the objectiof absorbing in partthe shocks or blows resulting from striking obstructions or,runn1ng into holes or ruts in the road, and of checkingthe rebound of the springs.

When the wheel of a running vehicle passes over a projection from the road surface, the axle is driven towards the frame of the vehicle and if it is not to strike the latter the energy of impact must be absorbed. The rate at which this energy is absorbed determines the force transmitted to the frame. As vehicles are commonly operated the greater part of the time over relatively even ground surfaces and only a small part of the. time over extremely irregular ground surfaces, it is better in practice to absorb as little as possible of the impact energy when the axle is at or near its normal position with respect to the chassis frame and to absorb an increasing proportion of this energy, preferably by means supplemental to the springs, as the axle approache'sthe frame. This will permit the use of softer or more flexible springs and is thus equivalent to favoring average operating conditions at the expense of the relatively rare extreme conditions, though the latter conditions, too, are taken care of in the best possible way from the standpoints of both car and rider. To accomplish this a shock absorber is necessary which will offer little or no resistance to spring compressing movement of the axle at or near its normal position but which will offer a resisting force increasing rapidly as the axle movesfrom its normal range of positions towards the chassis frame.

After the energy of impact from a road projection hasbeen absorbed the spring will tcnd'to return as much of this energy as it has absorbed to the axle and the frame, by imparting movements to these parts int-in verse proportion to their masses. As this would mean a further displacement of the frame, with the resulting discomfort to the occupants, .it is desirable to absorb this energy of spring rebound in the shock absorber.

The latter should therefore develop a force checking the rebound of the spring and the corresponding return of the axle from its po sition nearest the frame, which force may bev nicely graduated according to the stiffness of the spring and the masses involved.

When the wheel of a running vehicle passes over a depression in a road, thetweight of the wheel and axle and the spring force tend to force the wheel into the depression. ,To secure greatest riding comfort, this tendency must be retarded as the deeper the wheel penetrates into the depression the more severe will the shock be when it is driven out by the far side of the depression. It is desirable therefore that a shock absorber should resist a movement of the axle from its normal position away from the frame in an amount which can be readily determined to compensate for gravity and spring forces. This latter requirement coincides with that noted in the last preceding paragraph relative to absor'ption of the energy of spring rebound.

lVhen, however, the wheel has sunk into a depression, it should be as free as possible to rise out thereof, and a shock absorber should therefore offer the minimum resistance to movement of the axle from below normal position towards the frame.

The provision of resistance to movement of the axle from its normal position away from the frame for the purpose specified in next to the last'preceding paragraph, accomplishes the further important result of securing stability, especially-lateral stability, of the body of thevehicle notwithstanding the use of unusually soft or flexible suspension springs. 1

The chief objects of the present invention are comprised in the provision of a hydraulic shock absorber which is capable of meeting the above described conditions, which is not subject to trouble incident to the leakage of the working liquid and reliably performs its functions with a minimum of attention and which is characterized by relatively greatnected parts viewed in thedirection' indi-.

A piston is fixed to the piston rod (al),

whichpasses through a hole drilled "in the cylinder capfe), which is threaded in the lindrical portion cylinder (b). The piston in effect divides the cylinder into two chambers, V V (F) is a rocker shaft comprising thecylindrical portion (f) from which extend the arms.

(f), and also the arms (f'!) fixed to the cybtv means of keys (f"')'. The rocker shaft is carried in bearings formed half in the top part (a) and half in. p the middle part (a) of the casing (A). The

' arms (fi) are pivotally secured to the piston IO v rod (d). by means of the pin (9). The

arm (f' is pivotally secured to the links by means of thecylindrical pin (1a).,

I prefer to pivotally secure the links (2') to a prO ect'ion (9')- formed on the axle (k)-by means ofthe-cylindrical pin (Z), and to fix the casing (A) by means of a flange on the top part (a) to the frame (N).

For reasons which w1ll later be explained a the arms (f') are disposed at an angle between90 and 180 to the'arm (f) and the latter arm is in its normal posit-ion upwardly inclined from the horizontal.

Check valves (m) of any form in common use are provided at the bottomofthe cylinder (5) and in-the cylinder .cap (6) sodisposed as to permit the free movement of liquid into the cylinder chambers on the respective sides of the piston (d), but not out fromvthe said chambers. Ports and '(b') are provided in the walls of the. cylinder arranged substantially. as shown. I prefer to make the middle port. (b') [considerably larger than the other portsfor a purpose to be" set forth hereinafter.

A fluid, preferably glycerine, is introduced in the casing (A) in suflicient quantity to cover the cylinder The operation of the device is as follows:

- i )Vhen the axle moves (with respect to the frame (N) from its normal position with the 'vehicle loaded, as shown in full lines, to the position shown in dotted lines, as when.an

upward projection on the road surface is .en countered, the rocker shaft (F) is rotated, an

.the piston moves toward the bottom of that'movement-of the axle away from the the cylinder (6). During the first part of the motion of the piston (d) little resistance, is offered .to its motion by virtueof the fact that the several ports (-6" and, at the beginning of the movement, the port'(?g") permit the rapid outflow of the fluid contalned between the piston and the end of the cylinder (1;). Further movement of the piston (01) in the downward direction covers up suc- .cessively the ports (5'') one by one and as less area becomes thus available for the outflow of. the fluid, an increasing pressure of the fluid is required to maintain the outflow, and

fthis pressure reacts through .the mechanism to oppose the upward movement of the axle (ii) The rate of increase of the fluid pressure may be controlled at will by varying the number and sizes of the ports (6") In any case,

however, the resistance to the first part of the .rnovement referred to will be relatively with respect to the frame (N) shall be substa'ntially prevented beyond a certain predetermined point. i f

,While the diminishing'number for size of the ports (32") increase the resistance to the movement of the piston as it movestoward' the .end of the cylinder, the angular relation of the arms (7'') and (f' above noted, as the .axlesimultaneously approaches the frame, is

such that the force of the movement of the axle is transmitted through the links arm (f) and arms (f) with a marked creasing mechanical advantage. The result is that the stresses set up in the parts of the devicewithin the casing are corres ondingly diminished and said parts can be ma e correspondingly small and light. Furthermore, as the arm (f") approaches a vertical position'the stress to which it is subjected gradually changes from a bending to a tension stress. Consequently, the arm can be made lighter than otherwise would be possible and still be strong enough to sustain the increasing load. In other words, although the device is called upon effectively to resist an external springcompressing shock or force which is much greater than the spring expanding or rebound force which it must resist, the decreased mechanical advantage with which the greater force is'applied makes a liquid forc ing means which is strong enough only to resist the smaller of the external ,forces also [strong enough to resist the greater force.

When the axle (It) moves away from the pine (N)'the piston ((1) will move upward :the cylinder (b) I prefer-to so. dispose the ports (6") and to make them of such size frame (considering that said movement is at a lower velocity than the opposite movement incident to the shock of an obstacle encoun tered), will be resisted'in such a manner that the commonly known effect of recoil dampgreater than the resistance to the movement.

ing or checking may be obtained and also sudden movement of the axle below its normal position in relation to the frame may be resisted. When the axle is moving away from the point at which it is nearest to the frame ('N) the piston (03 is obviously moving upwards in' the cylin er (6). Little resistance is offered to such motion as long as the large central port (b"") isuncovered. Before the::pis'ton-reaches its normal-posi- 'tion, however, the port (2%") is covered by ""the piston, and from then on a greater re sistance is offered to the further upward movement of the piston. vThe upper ports (6") are of such size that the proper fluid pressures are developed to substantially absorb the recoilnenerggmirrrtheaspring, and dampen the oscillations of the latter. To accomplish this the resistance to the movement of the piston reaches a value at or near the normal position thereof which is materially of the piston in the opposite direction at its normal position. Thus the movement. of the axle away from the frame is resisted during the first part thereof by a forcethatis small in relation to the resistance at the end of said movement. Considered in another aspect, this resistance during the first part of the movement of the axle away from the.

frame is negligible, using the latter word in the sense noted above. Following this first part of the movement of the axle away from the frame, i. e., when the piston covers the large port (b), the resistance increases.

to an amountthat is clearly appreciable to an occupant of the vehicle. stood that in referring above to the normal position of the piston that I mean itsposition in the cylinder when the vehicle with normal or average load is standing still or moving over a smooth road surface. Such a position is illustrated by the full line showing in the drawing. The normal position of the shaft (F) is, of course, that corresponding to the normal position of the piston.

The spring recoil having been damped, the axle and frame are permitted to return relatively freely to their normal relative positions since the combined capacity of the large port (b") and the ports (6") offer a resistance to the piston that is negligible in the sense above noted and that, in another aspect of the matter, is small in proportion to the resistance at or near the end of the piston movement in the same direction. In this connection it is to be noted that the resistance tothe first part of the shock absorbing movement and the resistance to the first part of the movement that checks the spring recoil, in order to be negligible in the sense noted in each instance, may be different in absolute amount; and in the preferred practice the latter resistance will be less than the former.

It will be under- A vehicle equipped with, my improved shock absorbers may have relatively soft or flexible springs because a large part of the energy of shocks incident to assage over rough road surfaces is absorbed y the shock absorbers-and a lesseramount need be absorbed by the springs. And since the spring compression is left relatively free of resistance by the shock absorbers when the pistons of the latter are in the intermediate parts of their range of movement, full advantage is taken of the softness of the springs in pass- .ing over slightly or moderately rough road surfaces andas extremely rough road surfaces are only rarely encountered, the average riding qualities of the vehicle are vastly improved. Although unusually soft or flexible springs are used in securing this result the lack of 'stabilit which would ordinarilyattend the use of such springs is'obviated because the resistance offered-by the shock absorbers to separation of the frame and axle from each other, when they are at or near their normal relative positions, effectively resists side sway of the vehicle body. Along with the enhanced riding comfort referred tothereis naturally achieved a reduction in the wear and tear on the vehicle that results from passage over rough road surfaces.

Not only does my improved shock absorber satisfactorily perform the functions that have been pointed out, but by reason of the pivotal mounting of the cylinder within the casing a high degree of compactness is attained and by reason of this feature and the minimizing this connection it should be observed that the space surrounding thecylinder and occupied by the reserve or surplus liquid is of relatively large caliber so that any air in the casing that becomes mixed with the liquid due to the splashing or churning of the latter, readily separates from the liquid and rises again to the top of the casing. Thus the drawing of air into the cylinder is avoided and the reliable checking action of the liquid unmixed with air is secured.

Again, the fact that operative connection between the checking piston and the operat ing means external to the casing is effected by a rotatable shaft extending through the wall of the casing, makes it relatively easy to prevent leakage of liquid from the casing since the jointbetween the casing and a rotating shaft is readily made practically liquid 6U shaft, said liquid forcing means being prospects my construction-shown without departing from the invention as defined in the appended claims.

What Iclaim is:'- y I l v I 1. In a shock absorber for vehicles, the combination of. a casing forming a substan tially liquid-tight chamber; a body of liquidin said chamber; a shaft extending from the outside to the inside of said casing. through the wall thereof and rotatable in relation thereto; and double acting liquid forcin meansin' said casing comprising two liqui chambers and piston means movable therein 'and operatively connected to the said shaft,

said liquid forcing means being provided with meansafiordin and controlling liquid inlet to and outlet from the said chambers, the said chambers in the normal operation of the device havin communication with the said body of liqui and the said means affording and controlling-liquid inlet to and outlet from the'said chambers, ada ting the said forcing means to resist'the re ati've rotation of the said shaft in one direction by a force which is relatively small during movement fromone extreme to the intermediate normal position of said shaft and which 1ncreases to a maximum at a predeterminable relative rate as the'rotation procee'dsfrom said normal position to the opposite extreme,

. and to resist the relative rotation of the said shaft in the opposite direction by a' force which increases at a predeterminable relative rate from a relatively small value in that position in which the'resisting force is a maximum for the firstnamed movement, said forces varying furthermore with the speedof rotation of saidshaft;

2. In a shock absorber for vehicles; the combination ofa casin forming a substantially liquid-tight eham er; a body of liquid in said chamber; a shaft extending from the outside to the inside of said casing through the wall thereof'and rotatable in relation thereto; and double acting liquid forcing means in said casing comprising two liquid chambers and piston means movable therein and operatively connected to the said vided with means affording and controlling liquid inlet to and outlet from the said chambers, the said chambers in the normal operation of the device having communication with the said body .of liquid through openings. communicating with said liquid below the level thereof and the said means affording and, controlling liquid inlet to and outlet from the said chain ers adapting the said forcing means to resist the relative rotation of the said shaft in one direction by .a force which is relativelysmall during movement from one extreme tothe intermediate normal position of said shaft and which increases to a maximum at a predcterminable relativerate as sition to the opposite extreme, and to resist the relative rotation of the said shaft in the 3 opposite direction by a force which increases at a predeterminable relative rate from a relatively small value in that position in which the resisting force is a maximum for the'first-named movement, said forces varying furthermore with the speed of rotation of said shaft.

- 3. ,In a shock absorber for vehicles, the combination of a casing forming a substantially. 1

liquid-tight chamber; a bodylof liquid in said chamber; a shaft extending from the outside the rotation proceeds from said normal poto the inside of said casing-through the wall thereof androtatablein relation thereto; and

casing comprising two liquid chambers and piston means movable therein and operatively connected to the said shaft; said liquid forc-' ing means being provided with means affording and controlling) liquidinlet to and outlet from the said cham ers, and adapting the said forcing means to resist the relative rotationof the saidshaft in one direction by a force which is relatively small during movement from one extreme to the intermediate normal position of said shaft and which'increases to a maximum at a predeterminable relative rate as the rotation proceeds from said normal position to the opposite extreme, and to resist a the relative rotation of the said shaft in the opposite direction by a force which increases at a predeterminable relative rate from a relative'lysmall value in that position inwhich the resisting force is a maximum for the 'firstnamed movement to avalue at the normal position of the shaft which is greater than the a value of the resistance at the normal posijdouble ac'ting liquid forcing means in said tion of the shaft for the movement in the opposite direction, said forces varying furthermore with the speed of rotation of said shaft.

4. In a shock absorber for vehicles, thecombination ofa casing forming a substantially liquid-tight chamber; a body of liquid in said chamber; a shaft extending from the outside to the inside of said casing through the wall thereof and rotatable in relation thereto; and double acting liquid forcing means in said casing comprising two liquid chambers and piston means movable therein and operat'ively connectedto the said shaft, said liquid forcing means being provided -with means afi'ording andcontrolling liquid inlet to and outlet from the said chambers, the said chambers in the normal operation of the device having communication with the said body of liquid through openings communicating with said liquid below the level thereof and there being spaces for liquid betweensaid openings and the level of the liquid of large caliber adapted to insure free escape from the liquid of anyair mixing therewith during the operation of the device, and the said means affording and controlling liquid inlet to and outlet from the said chambers adapting the said liquid forcing means to resist the relative rotation of the said shaft in one direction by a force which is relatively small during movement from one extreme to the intermediate normal position of said shaft and which increases to a maximum at a predeterminable relative rate as the rotation proceeds from said normal position to the opposite extreme, and to resist the relative rotation of the said shaft in the opposite direction by a force which increases at a predeterminable relative rate from a relatively small value in that position in which the resisting force is a maximum for the first-named movement, said forces varying furthermore with the speed of rotation of said shaft.

5. In a shock absorber for vehicles, the combination of a casing forming a substantially liquid-tight chamber; a body of liquid in said chamber; a shaft extending from the outside to the inside of said casing through the wall thereof and rotatable in relation thereto; and double acting liquid forcing means in said casing comprising a double acting cylinder in the casing submerged in said body of liquid and piston means movable in the cylinder and operatively connected to the said shaft, said liquid forcing means being provided with means affording and controlling liquidinlet to and outlet from the two chambers of the cylinder, the said chambers in the normal operation of the device having communication with thasaid bodyof liquid and the said means affording and controlling liquid inlet to and outlet from the said chamber adapting the said forcing means to resist the relative rotation of the said shaft in one direction by a force which is relatively small during movement from one extreme to the intermediate 7 normal position of said shaft and which intially liquid-tight chamber; a body of liquid in said chamber; a shaft extending from the outside to the inside of said casing through the wall thereof and rotatable in relation thereto an arm fixed to the inner portion of said shaft; and double-acting liquid forcing means in said casing comprising a cylinder closed at both ends and completely immersed in the body of liquid in the casing, said c'ylinder being connected to the casing in a manner permitting the cylinder to swing about an axis parallel to the axis of said shaft, and a piston-in the cylinder having a rod extending through one end of the cylinder and directly pivotally connected to the arm on the inner portion of the shaft, said liquid forcing means being provided with means comprising ports through the walls of the cylinder and communicating with the body of liquid in the casing for controlling the flow of liquid into and out of the cylinder at each side of the piston; the last named means adapting the liquid forcing means to V resist the relative rotation of the said, shaft in one direction by a force which is relatively small during movement from one extreme to the intermediate normal position of said shaft and which increases to a maximum at a predeterminable relative rate as the relative rotation proceeds from said normal position to the opposite extreme, and to resist the rotation of the said shaft in the opposite direction by a force which increases at a predeterminable relative rate from a relatively small value in that position in which the resisting force is a maximum for the firstnamed movement, said forces varying furthermore with thespeed of rotation of said shaft.

7. In a shock absorber for vehicles, the

journaled in the wall thereof; an arm fixed to the inner portion of 'said shaft; and double-acting liquid forcing means in said casing comprising a cylinder closed at bioth ends and completely immersed in the body of liquid in the casing, said cylinder being connected to the casing in a manner permitting the cylinder to swing about an axis parallel to the axis of said shaft and a piston in the cylinder having a rod extending through the opposite end of the cylinder and directly pivotally connected to the arm on the inner portion of the shaft; said liquid forcing means being provided with means comprising ports through the walls of the cylinder and communicating with the body of liquid in the casing for controlling the flow of liquid into and out of the cylinder at each side of the piston. v

8. In a shock absorber for vehicles, the combination of a casing forming a substantially liquid-tight chamber; a body of liquidin said chamber; a shaft extending from the outside to the inside of said casing through the Wall thereof and rotatable in relation thereto; and double acting liquid forcing means in saidcasing comprising two liquid chambers-and piston means movable therein and opcratively connected to the said shaft, said liquid forcing means being provided'with means affordlng andcontrolling'.

liquid inlet to and" outlet from the said chambers, and adapting the said liquid forcing means to resist the relative rotation of the said shaft by a force varying with the speed of rotation and .further varying as follows:

, a (A) When the piston is moving from its normal position towards one end of the cylinder, the resisting force shall increase from a negligible quantity at or near such nor- -mal position, at a rate relatively predeter-.

minable, to a maximum near that end of the cylinder; When the piston is moving away from the end of the cylinder above re ferrcd to, the resisting'force :shall vary at. a relatively predeterminable rate from a negligible quantity at the said end to an appre'ciable quantity at or before the normalposition and to a maximum quantity at or near the-opposite end; (Q) When the piston is moving from the end of the cylinder opposite to that first above referred to, to-

- wards its normal position, the resisting force shall be negligible,

9. In a shock absorber for vehicles, the combinatlon of a casing forming a substantially liquid-tight chamber; a body of liquid insaid chamber; a shaft extending from the outside to the inside of, said casing through the wall thereof and rotatable in relation thereto; and double acting liquid forcing means comprising two liquid chambers and piston means movable therein operatively connected to the said shaft, the said liquid forcing means being provided with passages afiording and controlling liquid inlet to and "outlet from the said liquid chambers and the said passages adapting the said forcing means in the operation of the device to resist the relative rotation of the shaft in one direction by a force substantially' greater at approximately the end of such rotation than at any other pointithereof and to resist the relative rotation of the shaft 'in the other direction by a force which, be fore the shaft reaches normal position, has become appreciable though markedly less than the maximum force resisting rotation in-the first direction; r

10. In a shock absorber for vehicles, the combination of a casing forming a substantially liquid-tight chamber; a body of liquid in said chamber; a shaft extending from the outside to the inside of said casing through the wall thereof and rotatable in relation thereto; and double acting liquid forcing means comprising two liquid'chambers and piston means movable therein operatively -connected to the said shaft,'the said liquid -forci'ng means being rovided withpassa'ges affording and control ing liquid inlet toand outlet-from'the said liquld chambers, the ef fective cross-sectionalareas of the passages for one of said chambers being unequal to the effective cross-sectional areas of thepassages for theother chamber when the piston means is in normal position, andthe said; passages adapting the said forcing means. in the opera tion of thc device to resist the relative rota tion of the shaft in one direction'by a force substantially greater" at approximately the end of such rotation than at any other point thereof and to resist therelative rotation ofthe shaft in the other direction by a force wvhich, when the shaft reaches normal position, has become appreciable and greaterthan the force resisting the opposite rotation of the shaft in the same position thereof though 'markedlylessthan the maximum force resist-i 'ing the rotation in thesaid' opposite direction.

11; In a shock absorber for vehicles, the

combination of a casing forming a substantially liquid-tight chamber; a body of liquid 7 in said chamber; a shaftextending from the outside to the inside of said casing through the Wall thereof and rotatable inrelation thereto and double acting liquid forcing means in said casingcomprising two liquid chambers and piston means movable therein and operativelyconnected t0 the said shaft, said liquid forcing means being provided with means affordin and controlling liquid inlet to and outlet from the said chambers and adapting the said forcing means to resist the relative rotation of the said shaft in one direction by a force which is relatively small during movement from one extreme to' the intermediate normal position of said shaft and which increases to a maximumat a predetermina'bl'e relative rate as the rotation proceeds from said normal position towards the opposite extreme, and to resist the relative rotation of the said shaft in the opposite direction by a force which from the last named extreme to the intermediate normal position "of the shaft is at all times less than the said maximum and at or near the'intermediate normal position of the shaft is'greater than mace rection by a force which is relatively small during movement from one extreme to the intermediate normal'position of the piston means and which increases to a maximum at a predeteri'nined relative rate as the movement of the piston means proceeds from said normal position towards the opposite extreme,

intermediate normal position resisting the movement in the first named direction.

a 13. In a spring suspension for vehicles, the combination with the axle and the spring suspended frame of the vehicle of a shock absorber comprising a casing; a shaft eX-' tending from the outside to the inside of said casing through the Wall thereof and rotataole in relation thereto; double acting liquid forcing means comprising two liquid chambers and piston means movable therein and operatively connected to the said shaft; operative connections between the casing and the vehicle frame; a crank arm fixed to the said shaft; and operative connections between the crank arm and the axle; the said liquid forcmg means being provided with passages affording and controlling liquid inlet to and outlet from the said liquid chambers andv adapting the said forcing means to resist the relativerotation of the said shaft in one direction in relation to the casing by a force substantially greater'at approximately the end of such rotation than at any other point thereof and to resist the relative rotation of the shaft in the other direction by a force which, before the shaft reaches normal position, has become appreciable though markedly less than the maximum force resisting rotation in the first direction, and the operative connections-between the piston means and the axlebeing adapted to transmit force from the axle to the piston means with a-substantiallyrlower mechanical advantage when the shaft is at the end of its rotation in the first mentioned direction than when it is in its intermediate normal position.

In testimony whereof I hereunto affix my signature.

GORDON R. PENNINGTUll. 

